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D Atan, P Scanlon, V Grigoropoulos, E Johnson, C Foy, G Thomas, S Carter, JN Kirkpatrick; Digital Diabetic Retinopathy Screening - Reliability of Retinopathy Detection and Effect of JPEG Image Compression . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4388.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: (1) to assess the ability of the Topcon TRC NW55 camera with Sony DXC 950P CCD to detect micro-aneurysms in a TIFF digital format. (2) to determine whether the level of JPEG compression in our commercially available software affected the detection of these micro-aneurysms. (3) to determine how the detection of sight-threatening retinopathy would be affected by JPEG compression. Methods: The digital retinal images of 500 diabetic eyes in the TIFF format were graded by two experienced ophthalmologists. Ninety-seven eyes (19.4%) had micro-aneurysms less than 1 disc diameter from the centre of the fovea and one hundred and thirty-six eyes (27.2%) had referrable sight-threatening retinopathy, confirmed on slit-lamp biomicroscopy. After an interval of one month or more, the images were compressed to the JPEG format and were re-graded by the same ophthalmologists. Results: Less than 12% of the known micro-aneurysms were detected by both graders in either the TIFF or JPEG format, with kappa values of less than 0.1. However, the detection of sight-threatening retinopathy was comparable in both formats with kappa values for each grader of 0.65 and 0.62. Conclusion: This study has shown that the low resolution Sony camera, which is widely used in diabetic retinopathy screening programmes in the UK, is not adequate for the detection of mild background retinopathy. We would recommend the use of higher resolution cameras for this purpose.
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